Conventionally, as a method of collecting and analyzing a liquid collected from a living organism or the like, an analysis method is known which uses an analysis device that forms a liquid channel. The analysis device is capable of controlling a fluid using a rotating apparatus. Since the analysis device is capable of performing solution measurement, separating solid components, transferring and distributing a separated fluid, mixing a solution with a reagent, and the like by utilizing centrifugal force, various biochemical analyses can be carried out.
With an analysis device 501 described in Patent Document 1 (Japanese Patent Laid-Open No. 2007-78676) which transfers a solution using centrifugal force, as illustrated in FIG. 51A, after blood held in a separation cavity 70 is centrifugally separated by the rotation of the analysis device 501, the analysis device 501 is connected to a measurement channel 73 from a lower side of the separation cavity 70 via a connecting channel 71 and an overflow channel 72, whereby a blood cell component is capillary transferred. A blood cell component of a predetermined amount can be collected by trapping a blood plasma component remaining inside the connecting channel 71 in the overflow channel 72 by centrifugal separation and subsequently transferring only the blood cell component to the measurement channel 73. The blood plasma component trapped in the overflow channel 72 is drawn into an overflow cavity 74.
In addition, as illustrated in FIG. 55, Patent Document 1 is configured such that: a sample liquid is injected from an inlet 68 into a containment cavity 69 using an insertion instrument such as a pipette; the sample liquid is transferred to the separation cavity 70 and centrifugally separated by a rotation of the analysis device 501; a solution component is subsequently collected in the measurement channel 73 via the connecting channel 71; the solution component inside the measurement channel 73 is transferred to a measurement spot 76 by a next rotation of the analysis device 501; and, at the same time, unnecessary sample liquid inside the separation cavity 70 is discharged to an overflow cavity 78 utilizing a siphon effect of a connecting channel 77.
Conventionally, large-sized automatic analysis apparatuses capable of singlehandedly causing a reaction between a biological sample such as blood and an analytical reagent, and quantifying various components in the biological sample have been put into practical use and have become indispensible in the field of medicine. However, such apparatuses have not necessarily been introduced at all hospitals. In particular, there are quite a few small-scale medical institutions such as clinics that outsource sample analysis due to various reasons including operational costs. When adopting a system in which analysis is outsourced, a certain amount of time is required until analysis results are obtained. As a result, patients must inconveniently revisit the hospital in order to receive appropriate treatment based on the analysis results, or hospitals are disadvantageously inhibited from promptly responding to matters of urgency such as emergency patients.
In such a background, there have been demands from the market for an analysis apparatus with higher accuracy and a high degree of operational flexibility which is capable of reducing cost, reducing the amount of sample liquid required, reducing the size of the apparatus, and performing short-time measurement and simultaneous multiple measurement.
When contemplating the realization of an analysis apparatus with a high degree of operational flexibility, for example, the analysis apparatus ideally satisfies a condition in that the concentrations of a plurality of types of components can be measured in a short period of time at a high accuracy from a small amount of specimen collected by finger-prick blood sampling or the like. However, the amount of specimen that can be obtained by finger-prick blood sampling or the like without causing stress is, at the most, ten-odd microliters. As such, when a specimen in such a small amount is analyzed without modification, it is technically difficult to satisfy the aforementioned condition and, in particular, perform the analysis of a plurality of types of components at high accuracy.
As a solution to this problem, there is a method involving increasing the sensitivity of an analysis system and, by diluting a small amount of specimen with a diluent to increase the volume of the specimen, analyzing a specific component. In addition, diluents are frequently utilized not only as a measure against minute specimens but also when there is a high concentration of any substance or due to limitations in an analysis apparatus.
In recent years, the concentration of glycated hemoglobin in blood has become a prerequisite test item in terms of testing the progression of various diseases. Since, among other reasons, glycated hemoglobin that is a hemoglobin derivative enables judgment of normal-time blood sugar levels from which is excluded the dietary influence of blood sugar level variations, glycated hemoglobin is often measured for purposes of early detection of adult diseases. Also referred to as hemoglobin A1c, glycated hemoglobin is formed when glucose binds with hemoglobin in red blood cells and is quantified as a ratio (%) of glycated hemoglobin to hemoglobin. General methods for measuring glycated hemoglobin include HPLC (high-performance liquid chromatography), immunization, and borate affinity. In particular, in order to measure a ratio of existing hemoglobin A1c, an immunization requires that hemoglobin and hemoglobin A1c be individually measured.
Hemoglobin is generally measured by utilizing the specific optical absorption property of hemoglobin at wavelengths of around 415 nm or around 540 nm. Methods of measurement at wavelengths of around 540 nm include a cyanmethemoglobin method and an SLS hemoglobin method.
In addition, the measurement of glycated hemoglobin (hemoglobin A1c) by an immunization requires a process in which: hemoglobin be first extracted from red blood cells by hemolyzing a blood sample; and a three-dimensional structure of hemoglobin be altered to expose glycated portions of hemoglobin protein from the inside to the outside of the three-dimensional structure in order to judge whether hemoglobin is non-glycated hemoglobin or glycated hemoglobin (hemoglobin A1c). This process is known as hemoglobin denaturation. By further causing a reaction with an antibody that specifically identifies glycated portions, an amount of glycated hemoglobin (hemoglobin A1c) can be immunologically measured.
Known methods of optically analyzing a biological fluid using a glycated hemoglobin analysis device includes a reactive cassette for sequential reactive testing which involves non-centrifugal and non-capillary operations.
FIG. 52A illustrates a hemoglobin turbidimetry reactive cassette used for analyzing a biological fluid described in Patent Document 2 (Japanese Patent Laid-Open No. 03-046566). The described reactive cassette includes a container main body 400 having permeable surfaces as upper and lower surfaces, a capillary holder 401 containing a sample, and a diluent container 402 containing a diluent. An oxidant 403, an antibody particle 404, and a coagulant 405 are set in the container main body 400.
An analysis process by the reactive cassette involves inserting the capillary holder 401 having sampled a sample into the container main body 400 as illustrated in FIG. 52B, and supplying the diluent 406 from the diluent container 402 to the container main body 400. By tilting the container main body 400 as seen from FIG. 52B to FIG. 52C, the sample, the oxidant 403, and the diluent 406 are mixed inside a reaction channel 407. The mixed liquid is further transferred to the antibody particle 404 and to the coagulant 405. After a reaction process, the container main body 400 is set to the posture illustrated in FIG. 52C and a liquid mixture 409 is optically accessed from a window 408 to enable various biological analyses such as the turbidity of the liquid mixture 409.
Furthermore, known methods of optically analyzing a biological fluid which may be found in information provided in other prior art documents include a method described in Patent Document 3 (National Publication of International Patent Application No. 05-508709) in which analysis is performed using an analysis device in which a liquid channel is formed.
FIG. 53 illustrates an analysis device to be used for analyzing a biological fluid described in Patent Document 3. An analysis device 246 in which is formed a liquid channel is capable of controlling a fluid by centrifugal force through the use of a rotation apparatus. Since the analysis device 246 can measure sample solutions, separate fluid components through centrifuge, transfer and distribute separated fluid components, and the like, various biochemical analyses can be performed.
More specifically, a rotation apparatus 200 includes a sample receiving container 248 having a sample inlet port 250 and a diluent cavity 252 containing a diluent. Utilizing the centrifugal force caused by a rotation 218 of the analysis device 246, both a sample liquid and the diluent are transferred to a mixing cavity 205 where the sample liquid and the diluent are mixed through the rotation and deceleration of the analysis device 246. After a constant period of time, a condensed cellular component in the sample liquid is received in a separation cavity that is a cell-holding range 206 formed at an outer circumference in a radial direction of a receiving/mixing cavity 254. Subsequently, a liquid containing the cellular component is transferred to a fractionation cavity 260 via a flow limiting path 262, where the cellular component of the liquid containing the cellular component is further condensed by the rotation and deceleration of the analysis device 246 to be held in a cell-holding range 211 formed at the outer side of the fractionation cavity 260 in a radial direction. Meanwhile, a liquid containing no cells is transferred into a distribution path 266 and into an optical cuvette inside an analysis cavity 268 where a specific analysis is performed. Furthermore, when the sample liquid is blood and the cellular component is a blood cell component, the receiving/mixing cavity 254 and the fractionation cavity 260 can effectively extract and distribute a blood plasma component from which the blood cell component has been separated and removed.
As described, known analysis methods for measuring the amount of an analysis object existing in a liquid test sample include a method involving an analytical reaction with an analytical reagent and performing an analysis using spectrometry. Dedicated instruments such as analytical reaction containers or apparatuses to which the method is applied are particularly useful when implementing immunoassay that requires a large number of troublesome operational stages including the use of pipettes, mixing of a liquid test sample and an analytical reagent, and heating and incubation. In addition, the method eliminates the need of conveying such dedicated instruments to an inspection station and enables prompt in-situ measurement.
As illustrated in FIG. 54, Patent Document 4 (Japanese Patent Laid-Open No. 2004-150804) is configured such that: a sample liquid S injected into a liquid receiving unit 600 of an analysis device is transferred by centrifugal force and capillary action to a measurement spot 601B of the analysis device via a channel 601 of the analysis device; at the measurement spot 601B, a reaction is caused between a reagent portion 602 set to the measurement spot 601B and the sample liquid S; and a mixed liquid at the measurement spot 601B is optically accessed to read a color reaction of the mixed liquid.
An optical access by the analysis apparatus refers to irradiating the inside of the measurement spot 601B where the reagent has been dissolved by the sample liquid S and a color reaction is taking place with a light source mounted in the analysis apparatus, and detecting reflected light or transmitted light at a light receiving section. The concentration of a specific component in the sample liquid is converted from an absorbance (ABS), which is a logarithm of a ratio between irradiated light intensity and detected light intensity and is expressible asABS=log 10 (I/O),where I denotes irradiated light intensity (incident light intensity) and O denotes detected light intensity (outgoing light intensity),and from a so-called calibration curve, which is relational data between absorbance and concentration, stored in advance in the apparatus.
The analysis device is made up of a base substrate whose upper surface is formed with various depressions which form the channel 601, the measurement spot 601B, and the like, and a cover substrate that is bonded to the upper surface of the base substrate by an adhesive layer. The reagent 602 is carried and supported at the measurement spot 601B by dropping a requisite amount of the liquid reagent onto the measurement spot 601B before bonding the cover substrate to the upper surface of the base substrate. The analysis device is completed by bonding the base substrate and the cover substrate with an adhesive layer after the liquid reagent is cold cured or freeze-dried.